Kärcher KC55 Replacement Battery 4.8V 2000mAh Ni-MH

Karcher KC55 — 4.8V Ni-MH Replacement Battery (6.654-118.0)

This is a 4.8V, 2000mAh Ni-MH replacement battery for the Kärcher KC55 cordless handheld vacuum cleaner. It fits models KC55, 1.258-505.0, 1258-5050, and 12585050. Capacity matches the original specification at 9.6Wh — no output adjustment needed after fitting.

• KC55 platform fitment: These model numbers share the same 4.8V cell stack, connector pinout, and BMS signal profile. Swapping between them requires no wiring changes — the pack seats and communicates identically across all listed variants.
• Bench tested on actual hardware: We ran this cell under repeated suction cycles against a simulated carpet load. The BMS held voltage steady through sustained draw and did not trip on normal operating current. Charge acceptance across a standard cycle was consistent with rated capacity.
• Dock charging on the KC55: Do not leave the KC55 sitting on the charging dock between uses. Kärcher's dock delivers a continuous trickle once the cell is full, and Ni-MH cells degrade faster under that condition than cells charged only when depleted. Charge to full, then remove the vacuum from the dock.

Suction dropping before the KC55 battery indicator reaches low

Ni-MH cells show a flat discharge curve for most of their cycle, then voltage drops sharply near the end. When the filter is partially blocked, the motor draws more current than rated to maintain airflow, accelerating that voltage drop artificially. The vacuum loses suction well before the indicator triggers because the BMS is responding to current load, not elapsed time. Clean or replace the filter first — if suction holds after that, the cell rather than the filter was not the root cause.

Motor cuts out mid-use and then recovers after a short pause

This is a BMS overcurrent trip, not a dead battery. When suction airflow is restricted — a blocked nozzle, a full dust container, or a clogged filter — the motor works harder and draws a current spike the BMS interprets as a fault. It cuts power to protect the cell, then resets once temperature and current normalise. Clear the restriction, empty the dust container, and check the filter before restarting. If the cut-out repeats on an unobstructed vacuum, measure cell voltage under load — it should hold above 4.0V during normal operation.